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Now showing items 499-518 of 1932
  • Haarlaa, Rihko (Suomen metsätieteellinen seura, 1970)
  • Pietarinen, Juhani (Suomen metsätieteellinen seura, 1987)
  • Jutila, K. T. (Suomen metsätieteellinen seura, 1929)
  • Linnamies, Olavi (Suomen metsätieteellinen seura, 1951)
  • Olenius, Lauri (Suomen metsätieteellinen seura, 1951)
  • Sajaniemi, I. K. (Suomen metsätieteellinen seura, 1936)
  • Mustonen, Seppo E. (Suomen metsätieteellinen seura, 1965)
  • Sarvas, Risto (Suomen metsätieteellinen seura, 1938)
  • Parviainen, Jari (The Finnish Society of Forest Science and The Finnish Forest Research Institute, 1996)
    Nearly every forest stand in Finland has been burnt down by a wildfire at least once during the past 400–500 years. Slash and burn cultivation (1700–1920) was practised on 50–75 percent of Finland’s forests, while prescribed burning (1920–1990) has been applied to 2–3 percent of the country’s forests. Because of land-use changes and efficient fire prevention and control systems, the occurrence of wildfires in Finland has decreased considerably during the past few decades. Owing to the biodiversity and ecologically favourable influence of fire, the current tendency is to revive the use of controlled fire in forestry in Finland. Prescribed burning is used in forest regeneration and endeavours are being made to revert old conservation forests to the starting point of succession through forest fires.
  • Uuttera, Janne; Maltamo, Matti (The Finnish Society of Forest Science and The Finnish Forest Research Institute, 1995)
    Comparisons were made between artificially and naturally regenerated stands in the south-eastern part of North Karelia, Finland, and naturally regenerated stands in the western parts of the Republic of Karelia, Russian Federation. The effect of soil fertility and silvicultural operations on the stand structure was also investigated. The results of the study show clearly that when forests are artificially regenerated the stand structure includes less variation when compared with the stands naturally regenerated. Differences between the regeneration methods are clearer the more fertile the forest site is. Within the regeneration method there is also a clear trend in stand structure, with the variation decreasing the poorer the site. The effect of silvicultural operations, i.e. the cleaning of the sapling stand, has disappeared by the time of first thinning, although it appears to have a permanent effect on the dynamics of the tree species within a stand. The variation of the stand structure can be regarded as an essential factor for the potential biodiversity of the stand also at its young vegetation succession stage. This capacity for maintaining the forest biodiversity, developed at the young vegetation succession stage, becomes increasingly important in subsequent vegetation succession stages. Natural regeneration provides improved possibilities for the operations preserving forest biodiversity, as it generates more dense stands with a wider variation in stand structure, compared to artificial regeneration.
  • Skrøppa, Tore (The Finnish Society of Forest Science and The Finnish Forest Research Institute, 1994)
    After a presentation of basic biodiversity concepts, reviews are made of studies reporting genetic implications of tree improvement activities: seed treatments, seedling production, provenance transfers, plus tree selection, seed production in seed orchards, progeny testing. Several of the activities may influence the genetic structure and diversity of the planted forests. The general conclusion is, however, that planted forests are at least as genetically diverse as the natural stands that they replaced. The diversity in forest management and use is the best assurance for the future adaptability of the forests.
  • Tokola, Timo; Heikkilä, Juho (The Finnish Society of Forest Science and The Finnish Forest Research Institute, 1997)
    The purpose of this study was to test the benefits of a forest site quality map, when applying satellite image based forest inventory. By combining field sample plot data from national forest inventories with satellite imagery and forest site quality data, it is possible to estimate forest stand characteristics with higher accuracy for smaller areas. The reliability of the estimates was evaluated using the data from a standwise survey for area sizes ranging from 0.06 ha to 300 ha. When the mean volume was estimated, a relative error of 14 per cent was obtained for areas of 50 ha; for areas of 30 ha the corresponding figure was below 20 per cent. The relative gain in interpretation accuracy, when including the forest site quality information, ranged between 1 and 6 per cent. The advantage increased according to the size of the target area. The forest site quality map had the effect of decreasing the relative error in Norway spruce volume estimations, but it did not contribute to Scots pine volume estimation procedure.
  • Kilkki, Pekka (Suomen metsätieteellinen seura, 1968)
  • Steiguer, J. E. de; Royer, J. P. (Suomen metsätieteellinen seura, 1986)
  • Kuusela, Kullervo (Suomen metsätieteellinen seura, 1964)
  • Weissenberg, Kim von (Suomen metsätieteellinen seura, 1973)
  • Hökkä, Hannu; Alenius, Virpi; Penttilä, Timo (The Finnish Society of Forest Science and The Finnish Forest Research Institute, 1997)
    Models for individual-tree basal area growth were constructed for Scots pine (Pinus sylvestris L.), pubescent birch (Betula pubescens Ehrh.) and Norway spruce (Picea abies (L.) Karst.) growing in drained peatland stands. The data consisted of two separate sets of permanent sample plots forming a large sample of drained peatland stands in Finland. The dependent variable in all models was the 5-year basal area growth of a tree. The independent tree-level variables were tree dbh, tree basal area, and the sum of the basal area of trees larger than the target tree. Independent stand-level variables were stand basal area, the diameter of the tree of median basal area, and temperature sum. Categorical variables describing the site quality, as well as the condition and age of drainage, were used. Differences in tree growth were used as criteria in reclassifying the a priori site types into new yield classes by tree species. All models were constructed as mixed linear models with a random stand effect. The models were tested against the modelling data and against independent data sets.
  • Särkilahti, Eliisa; Valanne, Terho (Suomen metsätieteellinen seura, 1990)